The present invention relates to a numerical controller for displaying a state of machining of a wire electrical discharge machine.
In a wire electrical discharge machine, a wire electrode is disposed at a predetermined interval with respect to a workpiece, the workpiece and the wire electrode are immersed in a processing tank, and a voltage is applied between the workpiece and the wire electrode in this state.
The wire electrode and the workpiece are brought close to each other, and when the amount of the gap between the wire electrode and the workpiece reaches a predetermined amount, electrical discharge takes place between the wire electrode and the workpiece. As a result, the workpiece is machined by this electrical discharge energy.
In such wire electrical discharge machining, it is necessary to maintain the amount of the gap between the wire electrode and the workpiece to an optimum amount so as to constantly maintain an optimum state of electrical discharge. However, as the workpiece is machined, the amount of the gap constantly changes, and debris is produced between the electrodes, so that it is difficult to directly measure the amount of the gap.
On the other hand, in wire electrical discharge machining, a substantially linear relationship holds between the amount of the gap between the wire electrode and the workpiece and a mean working voltage obtained by smoothing the working voltage, and to maintain the mean working voltage to a fixed level is equivalent to holding the amount of the gap to a fixed amount. Accordingly, it becomes necessary to maintain the mean working voltage to a fixed level by controlling the machining speed or the position of the wire electrode.
As described above, in wire electrical discharge machining, a close relationship holds between the amount of the gap between the wire electrode and the workpiece on the one hand, and the machining speed and the working voltage on the other hand, and when analyzing the machining and determining whether it is good or bad, it is extremely important to use tendencies and movements of the machining speed and the working voltage as materials for their judgement.
As a conventional technique of this type, one disclosed in Japanese Patent Unexamined Publication No. 264215/1991 has been known. FIG. 7 is a diagram explaining a conventional example. In the left-hand portion of the drawing, a machining configuration based on a machining program is displayed in advance (broken-line portion), and the present position (thick-line portion) corresponding to the position of the wire electrode is displayed by being superposed thereon. In the right-hand portion of the drawing, the working voltage during machining and the time axis are graphically displayed as being the ordinate and the abscissa, respectively. Further, there is a disclosure wherein a portion of the machining configuration is selected and displayed in enlarged form, and the working voltage at the corresponding portion is displayed in enlarged form in interlocking relation to the enlarged display.
FIG. 8 is a diagram illustrating the relationship between the lapse of the machining time and the machining speed in the conventional example. However, in a case where machining is effected a plurality of times ranging from rough machining to finish machining with respect to the same configuration, since the relationship between the machining speed and the voltage in the respective stages is overwritten, there is a problem in that it is impossible to determine such as whether machining in each stage is being effected appropriately, or at which stage of machining a problem exists.
The present invention has been devised to overcome the above-described drawbacks of the conventional art, and its object is to provide a numerical controller having a display means which compares and displays in one two-dimensional graph items of machining-state detection information on machining stages ranging from rough machining to a plurality of times of finish machining.
In a wire electrical discharge machine for producing electrical discharge between a wire electrode and a workpiece and finishing the workpiece a plurality of times from rough machining to finish machining on the basis of a predetermined machining program, a numerical controller for a wire electrical discharge machine in accordance with a first aspect of the present invention comprises:
machining controlling means for determining and controlling a machining speed of the wire electrode in accordance with a discharge gap between the workpiece and the wire electrode or a state of electrical discharge;
machining-state detecting means for detecting machining-state detection information such as a working voltage for each movement of a predetermined distance in a process of execution of machining based on the machining program;
information-record storing means for correlating detection information detected by the machining-state detecting means, the machining speed generated by the machining controlling means, and machining position information for each movement of the predetermined distance, and for storing them in a storage device as machining-state detection information records;
information-record reading means for reading the stored machining-state detection information records from the storage device; and
two-dimensional graph displaying means for giving a graphic display by using the machining-state detection information and the machining speed, which are the machining-state detection information records thus read, as elements of one of two axes of a two-dimensional graph and by using the machining position information of the machining program as an element of the other axis thereof.
In a wire electrical discharge machine for producing electrical discharge between a wire electrode and a workpiece and machining the workpiece on the basis of a predetermined machining program, a numerical controller for a wire electrical discharge machine in accordance with a second aspect of the present invention comprises:
machining controlling means for determining and controlling a machining speed in accordance with a discharge gap between the workpiece and the wire electrode or a state of electrical discharge;
machining-state detecting means for detecting machining-state detection information such as a working voltage for each movement of a predetermined distance in a process of execution of machining based on the machining program;
information-record storing means for correlating detection information detected by the machining-state detecting means, the machining speed generated by the machining controlling means, machining position information for each movement of the predetermined distance, and at least one of a sequence number, a block number, a machining start hole number, and a number of finishing which are included in the machining program, and for storing them in a storage device as machining-state detection information records;
information-record reading means for reading the stored machining-state detection information records from the storage device; and
display means for displaying a list of the machining-state detection information records thus read.
A numerical controller for a wire electrical discharge machine in accordance with a third aspect of the present invention, the machining position information is displayed by being correlated to blocks of the machining program.
Since the present invention is configured as described above, the present invention offers the following advantages.
In the numerical controller for a wire electrical discharge machine in accordance with the first aspect of the present invention, the machining-state detection information, the machining speed generated by the machining controlling means, and execution portion information of the machining program are formed as a set and are stored in the storage device as the machining-state detection information records, and the stored machining-state detection information records are read from the storage device and are displayed in a two-dimensional graph.
Accordingly, it is possible to detect and determine whether rough machining or finish machining in each stage is being effected appropriately, or in which machining a problem lies in a midpoint machining stage due to changes in the machining speed, the working voltage, and the like.
In the numerical controller for a wire electrical discharge machine in accordance with the second aspect of the present invention, the machining-state detection information, the machining speed, and the execution portion information for correspondence with an execution portion, as well as the sequence number and the block number of the machining program, a cumulative distance of movement from a machining start point, a machining start hole number, and the number of finishing, are displayed in list form. Accordingly, it is possible to detect and determine whether rough machining or finish machining in each stage is being effected appropriately, or which position in the machining program is a problem in machining.
In the numerical controller for a wire electrical discharge machine in accordance with the third aspect of the present invention, since a display is given by using as a reference the distance of movement a point of origin in each block of the machining program, it is possible to detect and determine whether rough machining or finish machining in each stage is being effected appropriately, or at which position of the block a problem has occurred.